The aim of this research is to develop methods for evaluating the dependence liability of different classes of non-narcotic drugs. The research will employ drug self-administration techniques originally developed for studying self-administration of morphine in rats and monkeys. The research program will proceed in three phases: (1) Development of standardized drug self-administration procedures for determining the abuse liability of non-narcotic drugs using compounds which have been reported to be self-administered by animals. (2) Determination of the extent to which previously untested non-narcotic drugs which are subject to frequent abuse in humans will be self- administered by animals using the standardized procedure, and (3) Exploration of conditions which may increase the tendency to self- administer different classes of non-narcotic drugs.